The present embodiments relate to a medical radiotherapy assembly.
In radiation therapy using heavy ions, tumors are bombarded with accelerated particles. A particle accelerator forms a particle beam using a beam exit that is fixed in space. During the treatment, the patient must be put into an exact, predefined position, so that the tumor is located at the isocenter of the particle beam. Depending on the position of the tumor in the body, different irradiation positions (fields) are provided for the patient. For instance, the patient is positioned in either a horizontal or a sitting position in front of the particle emitter.
It is therefore necessary in the field of radiation therapy to determine the exact position of the tumor. For this purpose, imaging diagnosis methods are employed. German Patents DE 189 55 213 C2 and DE 189 27 022 C2 or in European Patent Disclosure EP 0 220 501 B1 disclose X-ray diagnostic devices. The tumor position is typically shown on the patient directly using external markings, skin markings, or on immobilizing masks.
Depending on the type and size of tumor, in therapy planning, the number of individual radiation treatments (fractions) required to securely destroy the tumor is defined. Typically, 20-30 radiation treatments over a period of several weeks are performed per patient.
Prior to the irradiation, the patient is brought to a radiation room with a beam exit window for the particle beam. The patient is immobilized or fixed on a patient support. The term “patient support” is understood here generally to include a cot or a chair on which the patient is immobilized. In accordance with the markings located on the skin or immobilizing masks, the patient is moved into the fixed isocenter that is marked by lasers, before the radiation therapy is begun. In addition to the beam exit window, a stationary imaging device is also provided in the radiation treatment room. The stationary imaging device can verify the tumor position from anatomical landmarks. After the verification, the patient is moved from his imaging position to an irradiation position.
Changes in the position of the tumor between the time of diagnosis and the time of each radiation treatment can lead to reduced effectiveness of the radiation therapy. The orientation of the patient into the isocenter based on the markings also involves imprecision. Even if the tumor position is verified immediately before the radiation treatment, exact positioning is difficult because the patient is moved from the imaging position to the irradiation position.